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Myelomeningocele

Myelomeningocele is a birth defect in which the backbone and spinal canal do not close before birth.

The condition is a type of spina bifida.

Alternative Names

Spina bifida; Cleft spine; Neural tube defect (NTD)

Causes

Normally, during the first month of a pregnancy, the two sides of the spine (or backbone) join together to cover the spinal cord, spinal nerves and meninges (the tissues covering the spinal cord). Spina bifida refers to any birth defect involving incomplete closure of the spine.

Myelomeningocele is a neural tube defect in which the bones of the spine do not completely form, resulting in an incomplete spinal canal. This causes the spinal cord and meninges (the tissues covering the spinal cord) to protrude from (stick out of) the child's back.

Myelomeningocele may affect as many as 1 out of every 4000 infants.

The rest of spina bifida cases are most commonly:

Spina bifida occulta, a condition in which the bones of the spine do not close but the spinal cord and meninges remain in place and skin usually covers the defect.

Meningoceles, a condition where the tissue covering the spinal cord protrudes from the spinal defect, but the spinal cord remains in place.

Other congenital disorders or birth defects may also be present in a child with myelomeningocele. Hydrocephalus may affect as many as 90% of children with myelomeningocele. Other disorders of the spinal cord or musculoskeletal system may be seen, including syringomyelia and hip dislocation.

The cause of myelomeningocele is unknown. However, low levels of folic acid in a woman's body before and during early pregnancy are thought to play a part in this type of birth defect. The vitamin folic acid (or folate) is important for brain and spinal cord development.

If a child is born with myelomeningocele, future children in that family have a higher risk than the general population. However, in many cases, there is no family connection.

Some theorize that a virus may play a role, since there is a higher rate of this condition in children born in the early winter months. Research also indicates possible environmental factors such as radiation.

Exams and Tests

Prenatal screening can help diagnose this condition. During the second trimester, pregnant women can have a blood test called the quadruple screen
. This test screens for myelomeningocele, Down syndrome, and other congenital diseases in the baby. Most women carrying a baby with spina bifida will have a higher-than-normal level of a protein called maternal alpha fetoprotein (AFP).

If the quadruple screen test is positive, further testing is needed to confirm the diagnosis.

Such tests may include:

Pregnancy ultrasound

Amniocentesis

Myelomeningocele can be seen after the child is born. A neurologic examination may show that the child has loss of nerve-related functions below the defect. For example, watching how the infant responds to pinpricks at various locations may reveal where the baby can feel the sensations.

Tests done on the baby after birth may include x-rays, ultrasound, CT, or MRI of the spinal area.

Treatment

Genetic counseling may be recommended. In some cases where a severe defect is detected early in the pregnancy, abortion may be considered. However, intrauterine surgery to close the defect (before the baby is born) is offered in some centers and appears to reduce the risk of some later complications.

After your baby is born, surgery to repair the defect
is usually recommended within the first few days of life. Before surgery, the infant must be handled carefully to reduce damage to the exposed spinal cord. This may include special care and positioning, protective devices, and changes in the methods of handling, feeding, and bathing.

Children who also have hydrocephalus may need a ventriculo-peritoneal shunt
placed. This will help drain the extra fluid from the ventricles (in the brain) to the peritoneal cavity (in the abdomen).

Antibiotics may be used to treat or prevent infections such as meningitis or urinary tract infections.

Most children will require lifelong treatment for problems that result from damage to the spinal cord and spinal nerves.

This includes:

Bladder and bowel problems: Gentle downward pressure over the bladder may help drain the bladder. Drainage tubes, called catheters, may be needed as well. Bowel training programs and a high fiber diet may improve bowel function.

Muscle and joint problems: Orthopedic or physical therapy may be needed to treat musculoskeletal symptoms. Braces may be needed. Many patients with myelomeningocele primarily use a wheelchair.

Follow-up examinations generally continue throughout the child's life. These are done to check the child's developmental progress and to treat any intellectual, neurological, or physical problems.

Visiting nurses, social services, support groups, and local agencies can provide emotional support and assist with the care of a child with a myelomeningocele who has significant problems or limitations.

Support Groups

Outlook (Prognosis)

A myelomeningocele can usually be surgically corrected, but the affected nerves may still not function normally. (The higher the location of the defect on the baby’s back, the more nerves will be affected.)

With early treatment, length of life is not severely affected. Kidney problems due to poor drainage of urine are the most common cause of death.

Most children with myelomeningocele will have normal intelligence. However, because of the risk of hydrocephalus and meningitis, more of these children will have learning problems and seizure disorders.

New problems within the spinal cord can develop later in life, especially after the child begins growing rapidly during puberty. This can lead to more loss of function as well as orthopedic problems such as scoliosis, foot or ankle deformities, dislocated hips, and joint tightness or contractures.

Symptoms of meningitis develop, including fever, stiff neck, irritability, and a high-pitched cry

Prevention

Folic acid supplements may help reduce the risk of neural tube defects such as myelomeningocele. It is recommended that any woman considering becoming pregnant take 0.4 mg of folic acid a day. Pregnant women need 1 mg per day.

It is important to remember that folic acid deficiencies must be corrected before becoming pregnant, because the defects develop very early.

Prospective mothers may be screened to determine the amount of folic acid in their blood.

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